Ceramics are often used as substrates for electrical circuitry, such as high-density and thin-film electrical circuits. However, printing of circuits on ceramic substrate surfaces which are not sufficiently flat and smooth typically causes formation of gaps in such circuits. Gaps formed during printing of circuits on ceramic substrate surfaces often causes electronic components employing the printed circuits to fail.
Ceramic substrate surfaces formed during densification of greenware precursors generally are not sufficiently flat or smooth to allow printing of electrical circuitry thereon. Camber of ceramic substrate surfaces is removed and sufficient smoothness is achieved, typically, by treating the surface of densified ceramic substrates. Examples of common treatments include grinding, lapping and polishing. Also, ceramic substrates often must be ground on two opposing surfaces in order to form ceramic substrate surfaces which are sufficiently flat.
However, such treatments typically are time-consuming and limit the quality of electrical circuits printed on the treated ceramic surface because defects, such as cracks, pits and voids, form in the ceramic surface. Also, the surface of ceramic substrates can be contaminated with grinding fluids, lapping compounds or polishing compounds. Removal of contaminants from ceramic surfaces generally requires further processing. Often, trace amounts of contaminants can not be removed from the ceramic surfaces, thereby limiting yields of circuits employing such ceramic substrates.
Cracks, pits and voids in ceramic substrate surfaces can cause circuits printed on the surfaces to be defective or to fail during use. Also, resistance values of ceramic surfaces of substrates can be deleteriously affected by the presence of imperfections and contaminants left on ceramic surfaces which have been ground, lapped and polished. Printed electrical circuits which include short-circuits or open circuits caused by imperfections in the ceramic surface of the substrate must be discarded. A significant portion of yield losses of printed electrical circuits is caused by imperfections of ceramic surfaces of substrates on which electrical circuitry is printed.
Thus, a need exists for ceramics having flat and smooth ceramic surfaces which minimize or overcome the above-mentioned problems.